USRE21931E - Tappet construction - Google Patents

Description

Oct. 21, `1941. c. #oom-HES ET AL Re- 21,931

TAPPET CONSTRUCTION Original Filed Ag. 3,1936 2 Sheets-SheevI l 5 l Q, ,52 v

2 Sheets-Sheva?. 2

c. voORHlEs ET Ax.

TAPPET CONSTRUCTION 4original Filed Aug. 3, 195e oct'. 21, 1941.

//"//////////l "ha Reuued Oct. 2l, 1941 UNITED STATES PATENT oFFIcE 21,931 p TAPPET CONSTRUCTION Carl Voorhies,

Grosse Pointe, Mich.,

signments, to Eaton Cleveland, Ohio, a co original No. 2,195,991,

Detroit, and Harry E. Voorhies,

Sssignors, Manufacturing rporation of Ohio dated January 2,

by mesne al- Company,

rial No. 94,040, August 3, 1936. Application for reissue June 25, 1941, Serial No. 399,699 t l 25 claimen (cl. 12s-9o) shown in the accompanying drawings in( which:

tappets of C The principal object of .the invention is to movement o1 the piston forming to its cylinde ation.

Other objects, features and advantages will become apparent from the following description and appended drawings. o

purpose oi illustrating the genus'of embodiments are 55 For the the invention, typical concrete o1' a portion of a y:an

Fig. l is -a central vertical section of a tappet construction according to this invention; c Figs' 2 and 3' are transverse sectionsxtaken substantially on the lines 2-2 and 3 9 of Fig. 1; Fig. 4 is a section showing a portion o! an internal combustion engine and showing a tappet Fig. 5 is a fragmentary view similar to Fig. 1

modified form of tappet construction; and.

Figs. 6, '1. 8 and numerals are applied to like parts in the lseveral views, and referring more especially to Figs. 1, 2 hydraulic compensating of the tappetbody Il. Liquid may be admitted through the recess 29 and port or ports 2i into the longitudinal bore 22. vfrom a. suitable source' of liquid supply, such as a. lubricating system of an internal combustion engine. The lower end of the tappet body indicated at 23 a hard wearcoxrbustion engine. 'I'he upper end of the cylindrical tappet body ii is open for the reception of the plunger i2 and the latteris provided with a cylindrical portion 25 adapted to make a free sliding i'lt within the bore 22. The cylindrical portion 25 is provided lflange 26 and 'preliminary or 21, is substantially normal to the axis of the plunger I2. The upper surface 2l of washer I6 is also a plain surface'and the cooperating surfaces 21 of flanges 26 and 26.0f washer .Il are both machined and polished so that when the washer is pressed upwardly by any material force leakage between the` flange 26 and washer Il is prevented.

The space 30 within the bore 22 of the tappet body Il, between the cylindrical portion 26 of plunger 'I2 and the valve member or washer I6 constitutes a preliminary or reserved liquid supply Vchamber for the tappet. The space within the bore 22 of tappet body II between the valve member or washer" Il and the bottom of the bore 22 constitutes the hydraulic compression chamber 3|. of the tappet. Expansion ofthe spring I3 tends to cause the plunger I2 to move outwardly with reference to the tappet body until the end of the plunger I2 contacts the .end of the valve 33, as indicated in Fig. 4, and to cau-se end 23 of tappet body II to contact the valve operating cam, or

tact other parts of valve operating mechanism. Outward movement of the plunger with reference to the tappet body creates a partial vacuum condition within the compression chamber 3| and causes the upper surface 26 of the valve member of washer Il to separate from the surface 21 of permits flow of liquid from the reserved chamber draulic compression chamber 3| until the latter chamber is iled with liquid and the pressure becomes substantially .equalized between the chambers 30 and 3|.4

The-lower face of the valve member orwasher Il is provided with a spiral groove 32 leading from its interior periphery to its outer periphery as indicated in Figs. 1 and 3. In actual practice this groove is of very small dimensions, and may be of otherform than spiral where the desired resistance to flow can be obtained. The spiralling or otherwise lengthening of the groove 32 permits the ,same to be of sumcient length to afford the desired resistance to flow of liquid from the interior to the outer periphery of the valve member and still permit the groove 32 to be formed by mechanical processes with a desired accuracy so that a definite cross-sectional area and length oi.' groove 32 may be had. This enables comanaal l i of the same dimensions as the washer elements -II and I5. The thickness of the washer I6, however, may be greater than that of either of the washers vI4 or I5. If desired, a downwardly flanged packing washer I1 havingv substantially the same inner and outer peripheral dimensions as the preceding washer-like elements and a light packing spring IB may -be employed for retaining the elastic packing washer I6, washer I5 and valve member I4 in position. The spring I8 is very light sothat any material difference in pressure between the preliminary. chamber 30 and the hydraulic compression chamber 3| will allow admission of liquid between the cooperating surfaces plunger I2 and the lesser pressure occurs in the hydraulic compression chamber 3I. The spring I8 and packing washer I1 may be omitted as illustrated in .the upper end of the plunger I2 and the lower end of the tappet body II con- 3II to the hymercial production of grooved washers or valve members by coining or stamping processes so that definite leak-down rates can'be obtained for large numbers of tappets with`a result'that uniform operation of all' of the tappets will be obtained. The washer I6 is preferably composed of metal and has its upper and lower surfaces plain and parallel, and these surfaces are machi'ned and polished so that undesired or inadvertent leakage between the surfaces thereof and the surfaces with which they cooperate will not occur.l ,The upper surface of the washer I6 cooperates vwith the grooved surface of the valve member of washer Il so that thegroove 32 provides la small cross-section passage preferably of extendedllength. the length of this passage tappets of the same type produced.

The washer Il is preferably composed of a rubber or other elastic andl substaninner and outer packing element Il are preferably substantially cross-sectional area and. 32 being uniform for all these elements.

l, is interposed Fig.' 9, later tobe described.

the tappet illustrated in Fig. in a valve operating mechanism in the manner indicated in Fig. 4. Oil may be admitted' through the annular recess 20 and ports 2| to the preliminary or reservechamber 30, from the conventional lubricating system of During operation fthe internal combustionengine. Plunger spring I3 holds the upper end of plunger I2 against the I valve stem, 'or an operating part therefor, and the closed end 23 of the tappet body against the cam shaft, or part operated thereby. When the plunger spring I3 causes outward inovement of the plunger with reference to the tappet body a partialvacuum condition will be created within the hydraulic compression 'chamber 3| and the valve member Il will not be held in tightengagement with the shoulder 26 on plunger I2. Oil then flows 21 and 28 of the flange valve member Y I4 from 26 on plunger I2 and the the preliminary chamber 3|) to hthe hydraulic compression chamber 3|.-

When the pressures are substantially equal in the chambers 36 and 3|, Il will be brought into contact with the surface 21 of ange 26 by the action of the light packing spring I6. As the cam shaft lifts the tappet body, the pressure of the oil in the hydraulic compression chamber 3| is increased on two l faces of the packing Yelement I6, the inner peripheral surface and the lower surface of the packing element I6, and will force the packing element against the wall off the bore 22 of the y and against the washer I5. The expansion of the packing element I6 against the wall of the bore 22'of tappet body II will effect a seal between the packing element and the tappet body, and the pressure of the sealing element against the washer I5 will effect a seal between This upward pressure is transmitted to the washer I5 forcing the latter into tight engagement with the valve member I4 so that no leakage can occur from the inner periphery of the valve member Il to the outer periphery thereof except such leakage as is allowed bythe spiral groove 32. This upward pressurelkewise forces the smooth plain upper face 28 of the valve Il against the corresponding face 21 on tappet body the flange 26 of plunger I2., Since the valve member Il i's pressed against the ange 26 by 70a force substantially equal to the entire load of the valve .gear at the time of opening of the engine valve, a seal 'between the valve member Il and flange 26 is effected.. When the engine valve is in closed position the pressure holding the valve member Il against the shoulder 21 andra of thesange ze on the valve member I4, provided between the cooperating surfaces the washer or valve element .-26 is released Iso that oil can seep betweenr surfaces of the washer elements Il and I6 and valve oi its seat at all times.

A'bounce oif of its` seat during its the between the valve member Il and the shoulder 26 so that a cleaning cycle is provided. The spiral groove 62, due tuv its added length, may be used to provide' for proper control of the leak-down rate of oil from the hydraulic com` pression chamber to the reserve supply chamber I without having the cross-sectional area ofthe i groove too small for manufacturing purposes. During lift of the engine valve the grooved face of the .valve member Il is pressed against the nat smooth face oi the washer I6 by a force stesi substantially equal to the entire load of the valve operating mechanism. In this manner, the engine valve will be elevated without appreciable lift loss except that provided for by the groove 32 which controls the leak-down rate of oil flow between the hydraulic compression chamber 3| and the preliminary .or reserve chamber 30.

As previously indicated the packing element or washer I6 is preferably composed of synthetic rubber, or other elastic but substantially incompressible material or expandable metal or alloy. A'I'he clearance between the inner periphery of the packing element I6 andthe cylindrical portion of the plunger I2 surrounded thereby, is perferably quite small sothat the` packing element I 6 is maintained in a substantially confined condition between the plungerv I2, the washer I6, the wall of bore 22 of tappet body II and the packing washer I1 on the oil within the hydraulic compression chamber II.

With the packing washer in substantially conned condition, elevation of the tappet by the operating cam shaft therefor will increase the pressure within the hydraulic compression chamber 3i and cause the packing element I6 to radially expand and effect a complete seal with the wall of the bore 22 of the tappet body II,

thereby to prevent possible' leakage of oil from. the compression chamber 3I past the packing element I6. vThe radial expansion of the packing element I6 thus occurring will, of course. increase its frictional engagement with the wall of the bore 22 tending to retard the downward movement of the plunger I2 in the bore 22 under leak down conditions, but such frictional drag will be insignificant as compared to the load required to be transmitted by the tappet in holding the valve open andwhich load is carried bythe oil in the compression chamber 3l. However, occasions do arise where a valve in seating bounces ofi o'f its seat, and under such conditions if both the plunger I2 and the packing element I6 were free to follow the valve upwardly under the iniiuence of the spring I3 when thus bounced, it will be appreciatedthat the resulting increase in `volume of oil in the compression chamber 3| would soon cause the tappet to become elongated to such an extentas to hold the With the construction herein provided should the valve thus closing movement, the plunger I2 wouldbe free under the influence of the spring I3 to follow the valve. Under such conditions the spring I6 would, of course, tend to move the sealing element I6 and its associated washers Il, I5 and II upwardly with the plunger but because of the friction exerted between the packing element I3 and the wall of the bore 22 such friction would cause a' the spring I6 being relatively light and being compressed under such conditions. The lagging oi the .element I6 ls preferably such thatr very little if any movement of the same would occur between the time thevalve thusbounces and again seats.v In this connection it will be appreciated that particularly where the packing element I6 is lformed of rubber-like or equivalent flexible material the pressure of the spring Il under the conditions above assumed will tend to 'expand the element I6 into frictional engagement with the bore 22 and thus increase its frictional engagement therewith to `enhance the retardation or lagging effect. It will be appre'- ciated that while it is relatively easyto pull a rubber `element through a bore it is relatively diilicult to push it through a bore and this eiect in the present case occurs under the conditions assumed. For the above reasons. with the particular construction shown and described, an exceptionally emclent seal is provided between the plunger and the wall of the bore while the tappet is carrying the load of the valve and at the same time the element I6 exerts a suilicient drag or retarding movement on the upward movement of the sealing element I6 and associated washers under the influence of the spring IB to eliminate the disadvantages which might otherwise occur` when the associated valve bounces from its seat.

Reference may now be had to Fig. 4 which illustrates a tappet of the construction described relative to Fig. l, interposed between a valve 33 of an internal combustion engine and an operating cam 34 fixed to cam shaft 35.' The operation of this arrangement will be clear from the above description of the construction shown in Fig. 1.

Referring to'Fig. 5, a'construction very similar to that disclosed in Fig. 1 is illustrated. In this construction the only modification is in the plunger I2' and relates to the manner in `which the lower end of the packing spring I8 is connected to the plunger. In the construction shown in Fig. 5 an element 36 is press fitted upon the reduced end 31 of plunger I2 in order to retain the lower end of packing spring I8 connected to the plunger I2 instead of clipped in a groove in the lower end of the plunger in the manner illustrated in Fig. 1. This construction, like that shown in Fig. l, provides a resilient packing element I6 of substantially incompressible material adapted to be forced into sealing contact with the wall of the bore of the tappet body II upon the occurrence of increased pressure in the hydraulic compression chamber 3i for substantially sealing the plunger I2' with respect to the tappet body II. Such increased pressures also cause the packing element I6 to be forced into sealing lengagement with the washer I5 and the valve member I 4 to effect a seal with the flange 26 of plunger I2'. The coined or'grooved lower surface of valve member I l and the upper surface of the washer I5 are also brought into contact so that the spiral groove in the lower face of valve member I4 aifords means for allowing only a definite and predetermined leakage or escape of oil from the hydraulic compression chamber 3|. The construction of the remaining elements and their arrangement is the same as that illustrated in Fig. 1'.

Reference may now be had to Fig. 6 which il` lustrates a modied form of tappet construction embodying the principl'pof the present invention, this construction *including a cylindrical tappet body 4I provided with a bore 42, which compression aii'ords the shoulder 43 for supporting a separate cylinder 44 adapted to be received within the upper end rof the bore142.

The tappet body, 4|l is providedwith an annular recess and an. admission port 45 and is otherwise of substantiallythe same construction as that disclosed in ythe embodiment showing in Figs.` land 5.- The separate cylinder 44 is provided with .a cylindrical bore y 41 and a.A reduced and bored boss portion 50 in which has been press fitted a suction tube 5I and a valve retainingfcage 52. A ball check valve 53 is disposed within the cage 52 for limited movement therein and is adaptedto make a fine line contact with the upper end of the bore of suction tube 5|, so that the upper end of the bore wall of tube 5i forms the valve seat for the return valve 53. The upper end of the cage 52 is provided with an oil passage 54. vThe separate cylinder 44 preferably makes a drop or sliding fit within the upper end of the bore 42 so that air may be. vented from the preliminary/or reserve liquid supply chamber 55 formed by that part of the bore 42 which lies below the separate cylinder 44. The tappet plunger 55 makes a loose or sliding fit within the bore 41 of separate cylinder '44. A cylindrical washer member 51 makes a similar fit within the bore 41 of separate cylinder 44 and is arranged within the latter bore immediately below the plunger 55. An elastic packing washer 55 and a packing retainer washer 5I are arranged within the bore 41 below the plunger 55 and washer 51 in the order named. A coil spring 52 is interposed between the boss portion 50 of separate cylinder 44 and the packing retainer washer 5|for extending the plunger 55 outwardly with reference to the separate cylinder until the upper end of the plunger contacts one element of a valve operated gear while the closed end of the tappet body contacts another.

An axial passage 53 extends upwardly through the packing retainer washer 5|, the elastic packing washer 50 and washer 51. That portion of the bore 41 of separate cylinder above the nonreturning valve 53 and below the washer elements 51, 55 and 5i constitutes the hydraulic compression chamber 54 of the tappet.

During operation of this tappet construction, oil or other liquid under pressure is admitted through the annular recess 45 and port 45 to the preliminary or reserve supply chamber 55. 'Ihe plunger spring 52 causes extension of `plunger 55 until the latter contacts one valve operating part and the closed end of the tappet body 4i contacts another valve operating part. Outward movement of the plunger 55 creates a partial vacuum condition within the hydraulic compression chamber 54 causing the valve 53 to lift from its seat and liquid medium to be drawn upwardly through the suction tube 5i into the hydraulic compression chamber 5 4 of the tappet. When an engine valve is lifted -by the tappet,

amai

the upper surface of washer 51 and the lower surface of ,plunger 55 likewise to be brought into intimate contact. The surfaces are pressed together by a force substantially equal to the entire load of the valve operating gear at the time of opening of the engine valve. The leak-down rate between the plunger and separate cylinder is controlled by the lower surface of the plunger 55 and the upper. surface of the washer,51, one of the surfaces either being grooved as indicated at 32 in the construction shown in Fig. 1 or one or more of these surfaces being leftfin a Sulliciently roughened condition, not polished, to provide the proper leak-'down rate between the plunger and the separate cylinder. In this construction the elastic but substantially incompressible element is substantially conned by the washer 51, separate cylinder 44, the packing retainer washer 5I and the oil or other liquid medium within the hydraulic compression chamber 54. Y Thus the elastic packing element 5|) v affords substantially the same effect in producing `a sealand a lagging or retardation of movement of the plunger with reference to the separate cylinder during operation as in the previously described constructions. The ball valve 53 is gravity and inertia actuated as well as by differential iluid pressures to cause its return to and maintenance in seated position during lift o f the tappet. 1

Referring to Fig. '1, a tappet very similar in construction to that shown in Fig. 6 is illustrated. In this construction the plunger 55', corresponding to the plunger 55 of the previously described embodiment isA provided with a reducedV end porseparate cylinder 44 of the previously described the increased pressure within the hydraulicv chamber 54 is exerted upon the inner periphery of the elastic but substantially incompressible packing element 5l and upon the lower surface Aof the latter, causing the material of the-packing to flow outwardly and provide a seal between the packing and thc bore 41 of the separate cylinder 44. The increased pressure exerted' by the liquid medium within the hydraulic compression chamber causes the adjacent surfaces of washer 51 and the elas- A tic packing element 55 to be pressed together andy embodiment, andthe abutment sleeve 56 is spaced a considerable distance from the reduced portion 55 of plunger 55'. The abutment sleeve. 55 limits outward movement of the plunger with reference to a separate cylinder so that in the -event that an engine valve becomes stuck in open position the plunger cannot follow the stuck valve a suiilcient distance to cause breakage of the latter or of the cylinder'head of the engine. The remaining parts shown in Fig. '1 correspond with like parts shown in Fig; 6 and are given thesame numerals.

Reference may now be had to Fig.' 8which discloses a further modified form of tappet construction. This construction includes a cylindrical body'portion 15 provided with a longitu- 'dinal bore 1I and a closed end 12 and is further provided with an annular recess 13 and one or more liquidadmission ports 14. A substantially hollow plunger 15 is received in the bore `1I of tappet body 10. The plunger 15 is provided with an annular Arecess 15 which conmiunlcates through port 14 with the annular recess 13 so that liquid under pressure or oil from the lubricating system of internal combustion engine may be supplied to the annular recess 15 which constitutes the preliminary or reserve oil supply chamber of the tappet. This tappet construction is designed primarily for overhead type of engine valves and the cylinder 15 is provided with an inwardly directed flange 11 for guiding a push rod, indicated at 18, and preventing the latter from jumping its seat. -A substantially spherical seat 5l! 'is provided at the upper end of a threaded member 8| which is threaded into f lower endof plunger 'liand provided with a head portiony 82 adapted ,to hold an elastic but sub,y `s'tantially incompressible packing element 03 in assembled relation with Vreference to the plunger the `l5. A The packing element 03 is downwardly flanged as indicated at Iill at the outer periphery t thereof. The seat member v| is axially bored as indicated at r05` for Y' lightness. The aat member BI is 'also providedV with a downwardly directed boss portion 86 adapted to contact thelower closed end 12 of the tappet bodyfll `in `the event yof failure o! oil supply so that after oil in the preliminary or reserve supply chamber 16 has been exhausted, the

tappet will still cause operation of the engine valve although with some lift loss. Axially directed peripheral passages 811 are provided at the lower endy of the plunger for permitting passage of oil or other liquid under pressure past the lower end of the piston from the` preliminary or reserve liquid supply chamber 'i6 to the hydraulic compression chamber 00 formed by that portion of the bore ll between the plunger l5 and the lower` closed end 12 of the tappet body 10.

lA plungerk spring 9| is disposed about the boss portion 86 and is compressed from free length by an amount only slightly more'than is needed for compensation purposes so that the plunger will not follow a stuck engine valve a suflicient distance to cause breakage by forcing the latter into a cylinder a suilicient distance to cause breakage of the valve or of an engine piston. The opposite ends of the plunger spring 0| abut the seat member 8| and the lower closed end l2 of tappet body 10 in order to forceI the plunger 15 outwardly with reference to the tappet body for compensation purposes.

Liquid under pressure or oil from the lubricat l ing system of the engine is admitted to the annular recess 'I3 and inlet port 1I through tire` draulic compression chamber 00 so that the elastic pecking 00 ailords the same sealing eilect and a lagging or retardation of movement oi' the plunger relative to the tappet body as inthe previously described embodiments,

Reference may now be had to Fig. 9 which discloses a tappet body |00 provided with an axially directed bore `|0| and closed at its lower end indicated at |02. The tappet body |00 is provided with a peripheral recess |03 and one or more admission ports |00 leading to an annular recess |00 cut into the wall portion of the tappet body |00 from'the bore |0| thereof. The recess |05 forms a part ot the preliminary or reserve oil or liquid supply chamber ot the tappet construction. Within the bore I0| are disposed a pair of pressed metal cup-like members |00 and |01, the member |00 being arranged in inverted position so that the open ends of the cup-like members iace'one another. The cup-like member |06 constitubes a par: of the plunger oi' the tappet construction whilev the cup-like'member |01 forms the separate cylinder.

riveted to the bottom of the inverted cup-shaped annular recess IIB outside the bottom portion of 1 the cup-like separate cylinder |01 and this recess communicates through the openings ||0 to pressible packing element 03 allowing oil o'r other Y liquid to pass from the preliminary or reserve supply chamber i0 through` the peripheral grooves or passages 01 and past the elastic packing 83 to the hydraulic compression chamber 90. As the'valve operatingcam starts to lift the tappet' increased pressures within the hydraulic compression chamber act on the lower surface of the downwardly directed iianged portion 00 oi' the elastic packing B3 and cause a flowing of the material of the elastic packing until the outer periphery thereof is brought into sealing relation with the bore 1| of tappet body '|0.` VThus in the present construction the elastic packing not only 4 serves to provide a seal between the plunger and the bore of the tappet body but'also provides a III on stem the exterior periphery of the tappet body, the

openings' ||0 being adapted to drop partially below the lower end oi the tappet guide for ventilation purposes and for lightening the tappet construction. In the event` of failure of the oil supply, the lower end o! the stem |00 will abut' the bottom of the separate cylinder member |01 after the liquid or oil in the preliminary chamber |00 has been exhausted so that the tappet will continue to lii't the engine valve, although with some lift loss. A plunger spring I Il engages suitable recesses in the inner peripheral surfaces oi' the open ends of the cup-like members |06 and |01 to extend the plungeroutwardly-with reference to the tappet |00. The preliminary or reserve supply chamber for oil or liquidcomprises a recess |00, the hollow interior o! the cup-like plunger |00 not occupied by the stem y |00, the portion of the hollow interior of the cup- |01 lying above the flange |00 and valve member ||2 and the space within the bore- |0| lying between the plunger Vand separate cylinder not' occupied by like separate cylinder the stem |00 and the spring 1. As in the previously deecribedembodiment, the plunger spring non-return valve controlling the admission ofoil or otherA liquid under pressure to the hydraulic compression chamber. tially incompressible packing, issubstantiall'y coniined by the plunger 15, the head portion 02 The elastic vbut substanof the seat member 0|, the Wall ofthe bore 1| of tappet body inland the on .or otheriiquid in hy- ||1 tends to extend the plunger |00 outwardly with reference to the tappet body until the upper end oi' the plunger contacts a valve operating part while the lower end of the tappet body |00 contacts another valve operating part. 'I'his tends to create a partial vacuum condition within` the hydraulic compression chamber |20 located in the bottom portion of the separate cylinder |01 so vthat the Superior in thereserve supply chamber |00 will force the valve member ||2 from its seat and cause now of oil or other liquid under'pressure from the re- A stem member |00 is oil pressure with serve or preliminary chamber and into the hydraulic compression chamber until the pressure within the chambers are substantially equalized. As the engine valve operating cam lifts thel tappet, the increased pressure within the hydraulic compression chamber |20 acts upon the lower face of the packing element H3 and upon its inner periphery to flow the material of the packing element outwardly against the bore of the .separate cylinder |01 thus sealing the packing element with reference to the separate cylinder and with reference to valve member ||2. The pressure against the lowrer surface oi' the packing element ||3 forces the valve member 2 upwardly against the flange ||I so that nearly a complete seal is established between the valve member ||2 and iiange member One or the other of the cooperating surfaces of the flange and valve member ||2 are either grooved as indicated in the embodiment shown in Figs. l and 5 or left in a slightly roughened condition until the proper 1eak-down rate is obtained between these elements in order to compensate radially outwardly by ilowing the material thereof in that direction in order to seal the plunger with reference to its cylinder, but when the engine valve is on its seat to permit air or gas to flow by gravity from the highest point of the hydraulic compression chamber past the plunger to the preliminary or reserve chamber in the embodiments shownin Figs. 1 to 5, 8 and 9 or directly to atmosphere in the embodiments shown in Figs. 6 and 7. In each of the illustrated embodiments provision is made for limiting travel inwardly of the plunger so that operation of the engine valve will be had, although with some lift loss, in the event of failure of oil supply and after oil in the preliminary or reserve supply chamber has been exhausted. In the embodiment shown in Figs. 1 and 5, the lower en d of the plunger |2 or the element 36 abuts the closed end 23 forl limiting 'inward 'movement of the plunger with reference to the tappet body. In the embodiment shown in -Figs. 6 and 7 the plunger and elements carried thereby have but a limited movement inwardly for the lengthening of valve operating parts due I 'to expansion under heat. In this construction the unit comprising the plunger, plunger spring and separate cylinder structure and contained y parts is reversible in the tappet body so that the 'tappet are relieved, will retard any tendency of the plunger 08 to move upwardly a material distance under the influence of the spring Also, lf desired, a Sylphon bellows may be used in place of theplunger spring IIT for a self-contained tappet.

In the construction shown -in Fig. 9 such elements as a. plain washer and a packing spring washer and packing spring I1 and I8 of the embodiment shown in Figs. 1 and 5 are omitted. In the construction shown in Figs. 1 and 5, essentially the same valve and sealing element con-f struction should be employed as in the case of the embodiment shown in Fig. 9.

In the embodiment illustrated in Fig. 9 the valve element ||2 is provided with a passage |2| extending therethrough in an axial direction so that when the pressure is relieved 'in the hydraulic compression chamber |20, the valve element may be readily separated from the flange and from the sealing element H3 in order to readily effect a cleaning cycle when the engine valve is on its seat. A vent opening- |22 is bored through the wall of the plunger element |00 near the upper end thereof to prevent trapping of substantial quantites of air or gas within the hollow interior of the plunger |06.

In all of the illustrated embodiments, the preliminary or reserve air separation chamber isvented to atmosphere either, through clearance between the plunger and the bore of the tappet body as in the embodiment shown in Figs. l to 5,

9 the lower end 'of the patent.

with reference to the separate cylinders 4l or M. In the construction shown in Fig. 8 the boss portion 86 and in the embodiment shown in Fig. stem member |08 serve the same ends.

The specific application of a lead or other soft metal and therefore ductile packing washer in a tappet of the construction herein described forms the subject-matter of our United States Letters Patent No. 2,227,288, issued December 3l, 1940, for improvements in Tappet construction, the sarne being a vdivision -of the original of this As many changes could be marie in the above 'construction and many apparently widely different embodiments of this construction could be had without departing from the scope thereof,

it isin-tended that all matter contained in the' above description or showing shall be inter-- preted as illustrative and not in a limiting sense.

What is claimed is:

1. In a valve tappet, the combination of a l cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and means including a yieldable but substantially incompressible element composed of rubber-like substance for causing a lagging or retardation in movement of said plunger relative to said cylindrical body when forces' acting axially upon opposite ends of said tappet are changed.

2. In a hydraulic valve tappet, the combination of a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a. plunger disposed in said bore and in `conjunction withI said cylindricalbody definv .drical body, of means including* a. yieldable but and 7. The elasticv packing elements .are forced substantially incompressible element composed of rubber-like substance in a substantially confined condition for causing a lagging or retardation in movement of said plunger relative to said cylindrical body when forces acting axially upon opposite ends of said tappetare changed.

3. ,In a hydraulic valve tappet, the combination of a cylindrical body provided with ay longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining ay hydraulic compression chamber 'betweemthe plunger and the closed end of said cylindrical body, means for admitting liquidto said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of means including a yieldable but substantially incompressible element composed of rubber- 7. Ina hydraulic valve tappet, the combination' 'with a cylindrical body provided with a longitudinal bore, said body being closed atone end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining the hydraulic compression chamber belike substance substantially confined by Said' plunger, said hydraulic compression chamber and said cylindrical body for causing a lagging or retardation in movement of said plunger relative to said cylindrical body when forces acting axially upon opposite ends "of said'tappet are changed.

4. A hydraulic valve tappet,- comprising a cylindrical body providedl with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed iii said bore and in'A conjunction with said cylindrical body defining a hydraulic compression chamber, means for admitting liquid into said cylindrical body and resilient means for extending said plunger outwardly with respectto said cylindricalibody, said plunger including at one end a cylindrical guide portion making a free sliding fit in the bore of said cylindrical body, and valve means carried by the opposite end of said plunger and including a yieldable but substantially incompressible element shiftable axially of the plunger substantially confined by the plunger, cylindrical body and the hydraulic compression chamber for effecting a seal between said plunger and cylindrical body.

5. A hydraulic valve tappet, comprising acylindrical body, provided with a longitudinal bore. said -body -being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body defining a hydraulic compression chamber, means for ad- Amittlng liquid into said cylindrical body and resilient means for extending said plunger outwardly with respect to said cylindrical body, said plunger including an annular flange providing a plain surface normal to the axis of said plunger,

tween the plunger and the closed end of said cylindrical bodihmeans for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of means including a yieldable but substantially incompressible element providing a seal between the plunger and cylindrical body and substantially preventing ow of liquid out of said hydraulic compression chamber, and means loosely mountedon said plunger` and providing for a definite and pre-determined escapement of liquid out of said hydraulic compression chamber.

8. In a hydraulic valve tappet, the combination with a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening the hydraulic compression chamber between the plunger and the closed end of a plain' surface valve disc positioned to abut at one face thereof the plain surface of said flange to provide a check valve, the other plain surface of said valve 'disc being provided with al groove second plain surface disc positioned to abut the grooved surface of said valve disc to complete a small cross-section passage of relatively long lengthfor limiting to a slight amount leakage from said hydraulic compression chamber, and a resilient but substantially incompressible element substantially confined r by said plunger, cylin'- drical body and hydraulic compression chamber for effecting a seal between said plunger and cylindrical body.

6. In a hydraulic valve tappet, the combination with a cylindrical body provided with'a longitudinal bore, said body being closed at one end of small cross-section and extended length, .i

said cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, of means including a washer-like element of yieldable but substantially incompressible material and providing a seal between theplunger' and cylindrical body for substantially preventing flow of liquid out of said hydraulic compression chamber and means loosely mounted on said plunger and providing for a dennite and predetermined escapement o f. liquid out of .said hydraulic compression chamber.

9. In a hydraulic valve tappet, the `combination with a cylindrical body provided with a' longitudinal bore, said body being closed at one end and open at the other', a plunger disposed in said bore and in conjunction with said cylindrical body defining the hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admitting liquid into said 'cylindrical body, and resilient means for extending said plunger outwardly with respect to l said cylindrical body, of means including a washer-like element of yieldable but substantially incompressible material and providing asealv between the plunger and cylindrical body for substantially preventing flow of liquid out of said hydrauliccompression chamber and means including a substantially rigid washer-like element provided with a 'small cross-sectioned groove in l one face thereof extending from its inner to its` and open at the other, a plunger disposed in said bore and in 'commotion with said cylindrical' body defining the hydraulic compression'chamber outer periphery and a second substantially rigid washer-like element provided with a flat surface adapted to contact the grooved 'surface of said first named substantially .rigid element providing l for a dolniteand predetermined escapement of between the plunger and the closed e`nd of said cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect' to said' cylindrical body,` of means including a flowable but substantially incompressible element for substantially preventing flow of liquid out of 'said' hydraulic compression chamber. and means loosely mounted on said plunger and providing for a definite and predetermined escapement of liquid fout of said hydraulic ,compression chamber. Y

liquid out of said hydraulic compression cham-.h

ber. a

10. In a hydraulic valve tappet, the combina# tion with a cylindrical body provided with av longitudinal bore and closed at one end, a plunger disposed in said bore and in conjunction with said cylindrical .body defining a hydraulic com pression chamber between the plunger and the closed end of-said cylindrical body, of means including a nowable 'but substantially incompresl sible velement for substantially preventing now oi liquid out of said hydraulic compression chamand providing a deiinit and predetermined escapement of liquidout of said hydraulic compression chamber,

l1. In a hydraulic valve tappet, the combination with a cylindrical body provided with a' longitudinal bore, said body being closed at one end and open at. the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening a hydraulic compression chamber between the plunger and the closed endo! said cylindrical body, means for admitting liquid into said' cylindrical body, and resilient means for extending said plunger outwardly with respect yto said cylindrical body, of valve means including a plurality of relatively movable parts movably tially complete seal between said plunger and said said hydraulic compression chamber.

l2. In combination, a hydraulic valve tappet interposed between an operating cam and an` engine valve and comprising a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, al plunger disposed in said bore and in commotion with said cylindrical body deilning a hydraulic compression chamber between the plunger and the closed end of said cylindrical body, means for admittingv liquid into said cylindrical body, resilient means for extending said plunger outwardly with respect to said cylindrical body, and valve means arranged between themeans for admitting liquid into said cylindrical body and said hydraulic compression chamber, said valve means including means eflecting a substantially complete seal between said plunger and said cylindrical body to prevent escape oi' liquid from said hydraulic compression chamber and including an imperfectly seating valve part providing for but limiting to a definite and predetermined amount, escape of liquid from said hydraulic compression chamber when the engine valve is open.

13. In a hydraulic valve tappet, the combina.- tion with a cylindrical body provided -witha longitudinal bore, said body being closed at one end and open at the other. a plunger disposed in said bore and in conjunction with said cylindrical body deilning a hydraulic compression chamber between the plunger and the closed end oisaid cylindrical body, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger 'outwardly with respect to said body, of non-return valve means including a yieldable element of ilowable but non-compressible material shiftable relative to the plunger, said yieldable element providing a seal between the plunger and cylindrical body' and providing a portion of said non-return valve means, said non-return valve means permitting passage of liquid into said hydraulic compression chamber but substantially preventing flow of liquid out of said hydraulic compression chamber.

14. In a hydraulic valve tappet, the combination with a cylindrical body provided with 4a longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body dening a hydraulic compression chamber and a liquid supply chamber, means-for admitting liquid into said cylindrical body, and means for extending said plunger 'outwardly with respect to said cylindrical body, of non-return valve meansl including a yieldable element of owable amai . mounted on said plunger for effecting a substanj but non-compressible material shiitable relative to the plunger, said yieldable element providing a seal between the plunger and cylindrical body and providing a portion of said non-return valve means, said non-return valve means permitting passage of liquid from said supply chamber to said compression chamber but substantially preventing ilow of liquid from said compression chamber to said supply chamber.

15. In a hydraulic valve tappet, the combination with a cylindrical body provided with `s. longitudinal bore, said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction' with said cylindrical body defining a. hydraulic compression lchamber between the plunger and the close'd end of said cylindrical body,'means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardly with respect to said cylindrical body, oi' non-return valve means including a yieldable element, said yieldable element providing a seal between the plunger and cylindrical body and providing a portion ofl said non-return valve means, said non-return valve means permitting passage oi liquid into said compression chamber but substantially preventing flow oi' liquid out of said compression chamber, said non-return valve means also including a pair lof disc-like elements having abutting plain surfaces, one of such surfaces being provided with a groove of relatively small cross-sectional area but relatively long length ior limiting to a slight amount leakage outwardly from the hydraulic compression chamber when said non-return valve `means is closed.

16. In 'a hydraulic valve tappet, the combination with a cylindrical body provided with a. longitudinal bore, said body being closed at one end and open at' the other, a plunger disposed in said bore and in conjunction with said cylindrical body deilning a hydraulic compression chamber and a liquid supply chamber, means i'or admitting liquid into said cylindrical bodyl and resilient means for extending said plunger outwardly with respect to said cylindrical body, .of non-return valve means including a yieldable element, said yieldable element providing a seal between the plunger and cylindrical body and providing a. portion of said non-return valve means, said non-return valve means permitting passage oi' liquid froml said supply chamber to said compression chamber, but substantially preventing return fiow of liquid from ysaid compression chamber to said,

supply chamber, said non-return valve means also including a pair of disc-like elements having abutting plain surfaces, one or such surfaces being provided with a groove o1' relatively small crosssectional area and relatively long length for limiting to a small amount leakage from said hydraulic compression chamber to said liquid supply chamber when said non-return valve` means is closed.

17. In a hydraulic valve tappet, the combinal a aussi cylindrical body and providing a portion of said non-return valve means, said non-return valve means permitting passage of liquid into said hydraulic 'compression chamber. but substantially preventing return flow i liquid out of saidcornpression chamber, said means including a washer-like element provided with a plain surface in which is formed a small cross-sectional groove extending spirally from its inner to its outer periphery for limiting to a slight amount leakage from said hydraulic compression chamber when said non-return valve means is closed.

18. In a hydraulic valve tappet, the combination with a cylindrical body provided with a longitudinal bore', said body being closed at one end and open at the other, a plunger disposed in said bore and in conjunction with said cylindrical body deiining a hydraulic compression chamber and a liquid supply chamber, means for admitting liquid into said cylindrical body, and resilient means for extending said plunger outwardlywith respect to said cylindrical body, of non-return valvemeans including a yieldable element, said yieldable element providing a seal between the plunger and cylindrical bodyand providing a portion of said non-return valve means, said non-return valve means permitting passage of liquid from said supply chamber to said hydraullc compression chamber but substantially preventing return flowof liquid from said hydraulic compression chamber to said supply chamber, said means also including a washerlike element provided with a plain ,surface in which is `formed a small cross-sectioned groove extending spirally from its inner to its outer periphery for limiting to a slight amount leakage from said hydraulic compression chamber to said liquid supply chamber when said non-return valve means is closed. v

19. In combination, a hydraulic valve tappet interposed between an operating `cam and an engine valve and comprising a cylindrical body proence oi.' the second mentioned means during operation.

21; In an hydraulic tappet, the combination of a pair of relatively movable members deiininga compression chamber, sealing means for said chamber, one of said members having a passage admitting iluid to said chamber, and an imperfectly seating valve means co-operating with said passage movable between an opened and a partially closed condition, said valve means being opened for relatively free flow during inflow of iiuid thereto and partially closed because oi' its imperfect seating for relatively restricted ow during outflow therefrom.

22. In an hydraulic tappet, the combination oi' a pair of relatively movable members defining a compression chamber, sealing means for said chamber, at least one of said members being provided with a passage admitting flow of iluid to and from said chamber, and imperfectly seating valve means adapted to open said passage for relatively free iiow of fluid and to partially close the same for relatively restricted ilow, said valve means opening said passage for relatively free inflow of fluid thereto during expansion of said chamber and partially closing said passage for relatively restricted outow therefrom during compression Aof said chamber.

23. In a valve tappet, the combination of a cylindrical body Provided with a longitudinal bore, saidbody. being closed at one end and open at the other, a plunger assembly slidably disposed in said bore and providing a compression chamber between it and the closed end of said bore, said assembly being providedwith a passage therein for the flow of oil into and out of saidv compression. chamber, and imperfectly seating valve means for controlling the iiow of oil through said passageway, said valve means permitting substantially free now of oil through said passageway to said compression chamber and permit-y ting a restrictedfiow of oil through said passage- `vided with a longitudinal bore, said body being yieldable but substantially incompressible valve element shiftablev relative to the plunger arranged in a substantially conned condition by said piston, said cylindrical body, and the-liquid in said hydraulic compression chamber, said valve element having an outside diameter equal to that of said plunger. l

20. Ina valve tappet, the combination of a cylindrical `body provided with a. longitudinal bore, said body being closed at one end and open at the other. means including a yieldable but substantially incompressible element composed of rubber-like 'substance slidably received in said bore and forming -a compression chamber between itl and the closed end of said bore, and means constantly urging the ilrst mentioned means in a direction to enlarge the 'volume o! said compression chamber, said element frictionally engaging the wall of vsaid bore whereby to cause a lagging or retardation in the, movement thereof outwardly ot said bore under the innusubstantially way from said compression chamber.

24. In a valve tappet, the combination of a cylindrical body provided with a longitudinal bore, said body being closed at one end and open at the other, a plunger assembly slidably disposed in said bore and providing a compressionchamber between it and the closed end of said bore,'said assembly being provided with a'passage therein for the iiow of oil into and out of said compression chamber, and an imperfectly seating valve means'for controlling the ilow oi' oil i Y bore, said body being closed at one end'and open vboth to and from said compression chamber through said passageway. l

25. Ina valve tappet, the combination of a cylindrical body provided with a longitudinal lat'the other end,a plunger slidably received in said bore. means including alvyieldable but sub- 'stantially incompressible element cooperating with said plunger to form a compression chamber between it and the closed end of said bore and urged toward equal movement with said plunger, and resilient means normally urging said plunger outwardly of said bore under operating conditions, sald element frictlonally engaging the wall ofk said bore whereby to cause a lagging or retardation in the movement thereof whenurged outwardly oi.' said bore with said plunger, whereby to retard the speed of enlargement o! said compression ychamber under the induence o! said resilient means.

. CARL VOQRHIES.

HARRY E. VOORHIES.

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